Current tool making methods and apparatus are used to shape parts in various industries. For example, the aircraft aerospace market and automotive companies have been working since the mid-1960s to develop composite parts or panels which will replace metal in airplanes and cars, respectively. Such composites can be made lighter in weight and thereby improve fuel economy in each market sector as a result of improved strength to weight ratios. To impart shape to such composite parts or panels, conventional technology may use tools made of graphite, Kevlar, or polyester.
Heat may be applied to the article in its formation stages to facilitate the creation of tight radii. Under conventional approaches, special precaution is needed to ensure that uneven heat transfer between the tool and the part do not create unwanted discontinuities in the resulting product. Uneven heat flow may be created when thermal capacity differs between thinner and more massive sections of the forming tool.
To indicate the background of the invention and illustrate the state of the art, J. Davy EPOXY TOOLING: EVOLUTIONS, APPLICATIONS, PERFORMANCE AND FUTURE, COMPOSITES FABRICATION, p. 17 (Feb. 1995) is incorporated herein by reference.
Current technology thus far has failed to solve problems often associated with incompatibility between the coefficients of thermal expansion of the tool and the article shaped thereby. Because of often differing coefficients of thermal expansion, a residual thermal stress is often created.